Factor out i2c lib

PUBLISHED_FROM=911d4100a44dbba3b6897835d7842fbbbf65d6ab

Author: dimonomid

mos.yml

@@ -9,6 +9,7 @@ filesystem:
 libs:
     # common mgos libs
   - origin: https://github.com/mongoose-os-libs/http-server
+  - origin: https://github.com/mongoose-os-libs/i2c
   - origin: https://github.com/mongoose-os-libs/ota-http-server
   - origin: https://github.com/mongoose-os-libs/rpc-loopback
   - origin: https://github.com/mongoose-os-libs/rpc-mqtt
@@ -26,8 +27,6 @@ libs:
   - origin: https://github.com/mongoose-os-libs/mjs
 config_schema:
   - ["i2c.enable", true]
-build_vars:
-  MGOS_ENABLE_I2C: 1
 
 tags:
   - js